AbstractThe preparation and characterisation of the 4‐(p‐phenylazophenyl)‐semicarbazones of pyridine‐2,3 and 4‐aldehyde, 2,3 and 4‐acetylpyridine, 6‐methylpyridine‐2‐aldehyde and pyridine‐2,6‐dialdehyde are described. These semicarbazones proved most useful for the isolation and characterisation of carbonylic pyridines. The preparation of the semicarbazones was carried out in dry ethanol and crystalline coloured products were o